OKICA IC card is a public transport IC card that can be used for travel on the Okinawa Urban Monorail (“Yui Rail”) line, or on bus routes on Okinawa Island operated by any of the following four companies: Ryukyu Bus Kotsu, Okinawa Bus, Naha Bus, and Toyo Bus (excluding scheduled tourist buses and limousine bus services).
So when you are in Okinawa you can not use a Suica card. Okinawa has its own IC Card.
You can purchase this card at the station at the ticket vending machines.
I would recommend this card so you don’t have to buy a ticket everytime you go by monorail or bus. It is a easy way to travel and you can alway recharge your card at the ticket vending machines.
How to use your card? Touch the card to the ticket gate to enter or exit. The fare for the section traveled will automatically be deducted and your card balance is displayed on the ticket gate.
For more information about transportation in Okinawa you can see this website.